From 6edb8a970e17a895d44c3b1401fbf9d02a1b7716 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 24 Apr 2023 09:45:58 +0200
Subject: Add support for machines mounts that span multiple physical devices

---
 doc/manual.cli |  6 ++++++
 init           | 68 ++++++++++++++++++++++++++++++++++++++--------------------
 2 files changed, 51 insertions(+), 23 deletions(-)

diff --git a/doc/manual.cli b/doc/manual.cli
index 5187e87..a994e9f 100644
--- a/doc/manual.cli
+++ b/doc/manual.cli
@@ -280,6 +280,12 @@ confirm over-provisioning, format the disk as \c{btrfs}, and label it as
 # ^D                           # Exit shell and reboot.
 \
 
+To create a single \c{btrfs} disk that spans multiple physical devices:
+
+\
+# mkfs.btrfs -L buildos.machines -d single -m single /dev/sda /dev/sdb
+\
+
 \h#config-net|Network|
 
 Network is configured via DHCP. Initially, all Ethernet interfaces that have
diff --git a/init b/init
index 0eed64d..f7bd6f5 100755
--- a/init
+++ b/init
@@ -327,7 +327,8 @@ echo -n '' >$fstab
 
 l=
 state=
-machines=
+declare -A machines
+machines_mode=
 while read l || [ -n "$l" ]; do
   d="$(sed -re 's/.*NAME=\"([^\"]+)\".*/\1/'   <<<"$l")"
   t="$(sed -re 's/.*FSTYPE=\"([^\"]*)\".*/\1/' <<<"$l")"
@@ -386,42 +387,29 @@ while read l || [ -n "$l" ]; do
     if [ "$l" = "machines" ]; then
       # Single mount.
       #
-      if [ -n "$machines" ]; then
+      if [ "$machines_mode" = "multiple" ]; then
 	error "multiple disks labeled with buildos.machines/machines.*"
       fi
 
       m=/build/machines/default
-      machines="single"
+      machines["$m"]="${machines["$m"]} $d"
+
+      machines_mode="single"
     else
       # Multiple mounts.
       #
-      if [ "$machines" = "single" ]; then
+      if [ "$machines_mode" = "single" ]; then
 	error "multiple disks labeled with buildos.machines/machines.*"
       fi
 
       n="$(sed -n -re 's/^machines\.([^ ]+)$/\1/p' <<<"$l")"
       m="/build/machines/$n"
-      machines="multiple"
-    fi
+      machines["$m"]="${machines["$m"]} $d"
 
-    info "mounting $d (buildos.$l) on $m"
-
-    # Check it.
-    #
-    if ! btrfs check -p "$d"; then
-      info "$d (buildos.$l) has errors; run btrfs check -p --repair $d"
-      error
+      machines_mode="multiple"
     fi
 
-    o="defaults,noatime,nodiratime,user_subvol_rm_allowed"
-    echo "$d $m btrfs $o 0 0" >>$fstab
-
-    # Mount it and change the owner of the filesystem root.
-    #
-    mkdir -p "$m"
-    mount -t btrfs -o "$o" "$d" "$m"
-    chown build:build "$m"
-
+    info "will be mounting $d (buildos.$l) on $m"
     continue
   fi
 done < <(lsblk --pairs --paths --output NAME,FSTYPE,LABEL)
@@ -437,13 +425,47 @@ if [ -z "$state" ]; then
   error
 fi
 
-if [ -z "$machines" ]; then
+if [ "${#machines[@]}" -eq 0 ]; then
   info "no disks labaled with buildos.machines* among:"
   lsblk --paths --output NAME,TYPE,FSTYPE,SIZE,LABEL,UUID
   info "consider formatting and/or labelling a suitable disk"
   error
 fi
 
+for m in "${!machines[@]}"; do
+
+  ds="${machines["$m"]}" # Array-like list of devices.
+
+  info "mounting $ds on $m"
+
+  # Check the devices and collect them in options.
+  #
+  fd=
+  o=
+  for d in $ds; do
+    if ! btrfs check -p "$d"; then
+      info "$d has errors; run btrfs check -p --repair $d"
+      error
+    fi
+
+    if [ -z "$fd" ]; then
+      fd="$d"
+      o="device=$d"
+    else
+      o="$o,device=$d"
+    fi
+  done
+
+  o="$o,defaults,noatime,nodiratime,user_subvol_rm_allowed"
+  echo "$fd $m btrfs $o 0 0" >>$fstab
+
+  # Mount it and change the owner of the filesystem root.
+  #
+  mkdir -p "$m"
+  mount -t btrfs -o "$o" "$fd" "$m"
+  chown build:build "$m"
+done
+
 # Create /build/tftp. We make it a size-limited tmpfs since potentially-
 # compromized VMs will be able to upload to.
 #
-- 
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